A gene controlling sex in grapevines placed on a molecular marker-based genetic map

Genetic maps of Vitis (2n = 38) have been constructed from an interspecific hybrid population of 58 seedlings of the cross 'Horizon' ('Seyval' + 'Schu yler') + Illinois 547-1 (V. cinerea B9 + V. rupestris B38). The maps were i nitially constructed based on 277 RAPD (random amplified polymorphic DNA) m arkers using a double-pseudotestcross strategy. Subsequently, 25 microsatel lites, 4 CAPS (cleaved amplified polymorphic sequence), and 12 AFLP (amplif ied fragment length polymorphism) markers were added to the maps. Another 1 20 markers, mostly those segregating 3:1, were also assigned but not positi oned on the linkage groups in the two maps. The 'Horizon' map consisted of 153 markers covering 1199 cM, with an average map distance of 7.6 cM betwee n markers. The Illinois 547-1 map had 179 markers covering 1470 cM, with an average map distance of 8.1 cM. There were 20 linkage groups in each map, one more than the basic number of chromosomes in grapes. Ten linkage groups in each map were identified as homologous using 16 microsatellite and 2 CA PS markers polymorphic in both parents. A single locus controlling sex in g rapes mapped close to a microsatellite marker. These maps provide enough co verage of the genome for QTL (quantitative trait loci) analysis and as a st arting point for positional gene cloning in grapes.